Abstract-The increasing digitalization of business and society has led to drastic changes within companies. Nearly all enterprises are facing enormous challenges dealing with topics such as Industry 4.0/Industrial Internet. With the goal of supporting companies to handle these challenges and "move" in an Industry 4.0 environment, several frameworks or reference models already exist. Here, we share the results of a detailed analysis of selected Industry 4.0 models. In particular, we foster in our analysis Lean Production aspects since the basic principles of Lean Management/Lean Production in existence since the 1980s have yielded appropriate measures to optimize production. These principles can and should be addressed and included by Industry 4.0 models as well. Our study provides a classification of 31 Industry 4.0 models/frameworks as well as the identification of needs for further research to enhance existing Industry 4.0 models more holistically.